1. Field of the Invention
The field of art to which this invention pertains is reactivation of oxidation catalysts and in particular, the reactivation of phosphorous-vanadium-oxygen complex catalysts which are used for the production of oxygenated products including aldehydes, ketones, acids and anhydrides. In a specified instance the aforestated catalysts can be used for the production of maleic anhydride from butane.
2. Description of the Prior Art
Relevant prior art includes U.S. Pat. No. 2,773,921 issued Dec. 11, 1956, having inventors Paul N. Rylander, Jr. and Wilford J. Zimmerschied. This patent was officially classified in Class 260-683.15 and generally relates to a phosphoric acid-vanadium pentoxide catalyst and a hydrocarbon conversion process using such a catalyst. In general, the patent teaches and discloses the use of a catalyst produced from the reaction of vanadium pentoxide and certain anhydrous phosphoric acids. It is especially directed towards polymerization processing. More specifically, the catalyst described and claimed in this reference is a reaction product of vanadium pentoxide and an acid selected from the group consisting of anhydrous orthophosphoric, pyrophosphoric or triphosphoric acids.
Other art which may be pertinent includes the use of chlorides or chlorine in maintaining catalyst activity in reforming or other similar processing. In the case of reforming, chloride addition is utilized to maintain a certain chloride level on the catalyst thereby keeping its acidity high enough for sufficient hydrocracking of paraffins.